College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 6 - Matrices and Determinants - Cumulative Review Exercises (Chapters 1-6) - Page 658: 6

Answer

$x=1$

Work Step by Step

We are given the equation: $\log_3 x+\log_3 (x+2)=1$ Use the product property of logarithms: $\log_3 x(x+2)=1$ Write the equation in exponential form: $x(x+2)=3^1$ $x(x+2)=3$ Solve the equation: $x^2+2x-3=0$ $x^2+3x-x-3=0$ $x(x+3)-(x+3)=0$ $(x+3)(x-1)=0$ $x+3=0\Rightarrow x_1=-3$ $x-1=0\Rightarrow x_2=1$ Check the solutions: $x_1=-3$ $\log_3 (-3)+\log_3 (-3+2)\stackrel{?}{=} 1$ The logarithms are not defined for $x=-3$!!! $x_2=1$ $\log_3 1+\log_3 (1+2)\stackrel{?}{=} 1$ $0+1\stackrel{?}{=} 1$ $1=1\checkmark$ The only solution is $x=1$.
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